Large sized lithium ion batteries have been used to supply high capacity electricity to electric vehicles and electronic devices that have become popular in recent years. Accompanying widespread use of lithium ion batteries, countermeasures for the treatment of used batteries are becoming important.
When processing lithium ion batteries, treatment of the electrolytic solution becomes a problem. For example, if an electrolyte (fluorine compound) contained in the electrolytic solution comes into contact with moisture in the air, harmful corrosive gases are generated. Conventionally, in order to ensure safety during operation, generally, lithium ion batteries have been incinerated, utilizing the fact that an organic solvent is used as the electrolytic solution. However, since corrosive gases generated during the incineration treatment cause damage to the equipment, measures to protect the equipment are required. Further, if the incineration treatment is carried out, it becomes difficult to reuse the battery constituent members of the lithium ion batteries.
As another treatment for a lithium ion battery, a method has been proposed in which a lithium ion battery is frozen below the melting point of the electrolytic solution, and then the battery is disassembled and crushed while frozen. With this method, generation of corrosive gases can be suppressed. However, such a method requires large-scale freezing equipment, so there are problems in terms of cost and installation space.
Japanese Laid-Open Patent Publication No. 2013-229326 discloses a method for safely recovering an electrolytic solution. More specifically, at first, volatile components of the electrolytic solution containing a fluorine compound are heated and vaporized in a reduced pressure environment. Next, the harmful fluorine components contained within the vaporized gas are reacted with calcium and solidified in the form of calcium fluoride, together with recovering an organic solvent component contained within the vaporized gas. The recovered organic solvent component, in the form of an organic solvent from which fluorine has been removed, is used as a fuel or the like.
Japanese Laid-Open Patent Publication No. 2013-109841 discloses a method for reducing the pressure of a lithium ion battery to a specified pressure range, together with raising the temperature thereof to a specified temperature range, and then opening a pressure relief valve to remove an organic solvent from the lithium ion battery.